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## 4th grade

### Unit 14: Lesson 9

Money word problems# Word problem: making change

CCSS.Math:

Sal solves how much change Charles will get after his purchase. Created by Sal Khan.

## Want to join the conversation?

- If I had $220 and the iPhone apple cost $130 than how many apples could I buy?

And how much of change would I get?(6 votes)- You could buy 1 iPhone. You would get $90 in change.(5 votes)

- who dosent know how many cents are in a dollor?(4 votes)
- I know what it is 100(2 votes)

- this really helped with my homework(3 votes)
- Tysm! I am starting to learn this at school. You really helped me a lot(3 votes)
- Why doesn't Sal show his work? Won't people get confused, "Wait, is 5x47 really 235"?(3 votes)
- is there an esyer way to do 5 times 47 or not(0 votes)
- how is a fraction simplified(3 votes)
- First, find the highest number that can divide into both the numerator and denominator exactly. Then divide the numerator and denominator by that number. If it's an improper fraction (the numerator is larger than the denominator), make it a mixed number. :)(0 votes)

- why do you have to times in money?(1 vote)
- So multiplication is a shortcut for adding the same thing over and over, so you never HAVE to multiply. If you have 5 apples that each cost 47 cents, you could add .47+.47+.47+.47+.47, but most people prefer to multiply 5*.47.(3 votes)

- math is so boring but awsome(2 votes)
- You make it so much easier to do this because you taught me one more way to solve the problem(2 votes)

## Video transcript

Charles bought 5 apples
that cost $0.47 each. He paid with a five-dollar bill. How much change did
Charles receive? So let's think about
everything in cents since they gave us the
cost in terms of cents. So first of all, how much
would the 5 apples cost? Well, we got 5 apples. 5 apples-- let me do
that same green color. We have 5 apples, and
each of those apples are going to cost $0.47. So 5 apples times
$0.47 per apple, this will give us the total cost
of the 5 apples in cents. So what's 5 times 47? Well, let's see. 5 times 40 is 200. 5 times 7 is 35. So it's going to be 235 cents. So it's 235. And just to remind
ourselves, this is 235 cents. Now, how much did he pay? He paid with a five-dollar bill. Well, a five-dollar bill is
going to be how many cents? Well, let's think about it. A five-dollar bill times
100 cents per dollar, he's essentially
paying with 500 cents. So this right over
here is the cost, and then this is what he paid. So we could figure
out how much change he needs to get back
in terms of cents. So he paid 500. The cost was 235. 235, so we just
need to subtract. And you might be able
to do this in your head. But in case you can't,
we can solve this. We can do this by regrouping. We have a 0 in the ones place. We have a 0 in the tens place. But let's try to regroup
from the hundreds place. We could take one
of the hundreds, so now we have only 400 left. And a hundred is
equal to 10 tens. So we could put a 10
in the tens place. But then we could take
one of those tens away, so we only have 9 tens. And if you took a 10 away, then
you put that in the ones place, it's going to become a 10. And now we're ready to subtract. So we are left with
10 minus 5 is 5. 9 minus 3 is 6. 4 minus 2 is 2. So how much change
does Charles receive? Well, it would be 265 cents. If we wanted to write
this in terms of dollars, we already know that there
are 100 cents per dollar. So you could view this as
200 cents plus 65 cents. And 200 cents-- well, this is
two groups of 100 cents, or $2. So this right over here
is $2 and 65 cents. Or you could view this--
because 65 cents is really 65 hundredths of a dollar. You could view this as $2 and
65/100 of a dollar, or $2.65. So that's how much change
Charles should receive.